Trump's immigration crackdown is reshaping federal law enforcement

 NBC News -  The Trump administration's largest immigration crackdown yet is underway, but the reallocation of personnel from other federal law enforcement agencies in order to carry out "Operation At Large" is causing tension among some officials who feel they've been taken off core national security missions.

The new ICE-led initiative is a response to frustration from White House chief of staff Stephen Miller over what he saw as numbers of arrests and deportations of unauthorized immigrants that were too low. Miller is so frustrated, two sources said, that he has berated and threatened to fire senior ICE officials if they did not begin detaining 3,000 migrants a day. He also threatened to fire leaders of field offices posting the bottom 10% of arrest numbers monthly.

According to the operation plan, the initiative calls on help from thousands of personnel, including: 

→ 3,000 ICE agents, including 1,800 from Homeland Security Investigations, which generally investigates transnational crimes;

→ 2,000 Justice Department employees from the FBI, U.S. Marshals Service and the DEA;

→ 500 employees from Customs and Border Protection; and 

→ 250 IRS agents, some of whom may be used to provide tax information on the whereabouts of immigrants using tax information, and others who would have the authority to make arrests. 

The operation is the latest example of how President Donald Trump's push for mass deportations is reshaping federal law enforcement, leaving less time and attention for other types of criminal investigations.

Now, FBI agents are joining in on immigration-related law enforcement operations, and DOJ teams focused on other issues are being disbanded so members can dedicate their time to immigration and other administration priorities. Federal courts are regularly seeing misdemeanor cases for border crossings, a rarity in recent years. And federal cases without immigration components have stalled or are moving more slowly. 

"There is such a priority on making immigration arrests that it takes longer to get answers on anything else," a law enforcement official said. "Something that used to be resolved in a matter of days now takes weeks."